1. Field of the Invention
The invention relates a process and an installation to secure a prestressed concrete pressure vessel for a nuclear reactor plant, surrounded by a protective reactor building, said reactor plant comprising within the prestressed concrete pressure vessel a gas cooled high temperature reactor, steam generators and blowers and being equipped within the reactor protection building with an operational gas purification apparatus and with storage vessels for the cooling gas connected with said purification apparatus, and an air circulation installation connected with an exhaust stack by means of a filter system, to prevent release of radioactivity to the environment.
2. Description of the Prior Art
In a known nuclear power station THTR-300 the cooling gas leakages escaping in normal operation and in the case of minor accidents from the reactor pressure vessel and from radioactive loops are exhausted by means of an air circulation installation comprising an exhaust blower and a filter system to an exhaust stack. In the case of accidents whereby major leakages are released, however, these leakages are exhausted without filtering through the exhaust stack to the environment, as the reactor protection building surrounding the reactor pressure vessel is not laid out for full pressure.
West German Application No. P 32 12 265 shows a process for the planned exhausting of activities from the reactor protection building of a nuclear reactor installation comprising a gas cooled high temperature reactor, said process comprising a discharge path consisting of a filter system, exhaust blower and a stack for cooling gas leakages occurring during normal operations. In order to secure the release of pressure on the reactor protection building even in the case of major cooling gas leakages from the primary loop and to assure the filtered discharge of such leakages to the environment, the known process provides that upon the occurrence of an accident with major cooling gas leakages the normal discharge path is automatically closed by means of a check valve and when a predetermined pressure is exceeded, a second discharge path largely paralleling the first one, is opened automatically or manually. In this second discharge path, installations are provided for the reduction of temperature, the deposition of fission products and the filtering out of gaseous fission products and suspended particles.